systemless 0.12.5

High-Level Emulation for classic Macintosh applications
Documentation 
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//! Shared conversion between classic Mac Roman bytes and Unicode text.

const MAC_ROMAN_HIGH: [char; 128] = [
    '\u{00C4}', '\u{00C5}', '\u{00C7}', '\u{00C9}', '\u{00D1}', '\u{00D6}', '\u{00DC}', '\u{00E1}',
    '\u{00E0}', '\u{00E2}', '\u{00E4}', '\u{00E3}', '\u{00E5}', '\u{00E7}', '\u{00E9}', '\u{00E8}',
    '\u{00EA}', '\u{00EB}', '\u{00ED}', '\u{00EC}', '\u{00EE}', '\u{00EF}', '\u{00F1}', '\u{00F3}',
    '\u{00F2}', '\u{00F4}', '\u{00F6}', '\u{00F5}', '\u{00FA}', '\u{00F9}', '\u{00FB}', '\u{00FC}',
    '\u{2020}', '\u{00B0}', '\u{00A2}', '\u{00A3}', '\u{00A7}', '\u{2022}', '\u{00B6}', '\u{00DF}',
    '\u{00AE}', '\u{00A9}', '\u{2122}', '\u{00B4}', '\u{00A8}', '\u{2260}', '\u{00C6}', '\u{00D8}',
    '\u{221E}', '\u{00B1}', '\u{2264}', '\u{2265}', '\u{00A5}', '\u{00B5}', '\u{2202}', '\u{2211}',
    '\u{220F}', '\u{03C0}', '\u{222B}', '\u{00AA}', '\u{00BA}', '\u{03A9}', '\u{00E6}', '\u{00F8}',
    '\u{00BF}', '\u{00A1}', '\u{00AC}', '\u{221A}', '\u{0192}', '\u{2248}', '\u{2206}', '\u{00AB}',
    '\u{00BB}', '\u{2026}', '\u{00A0}', '\u{00C0}', '\u{00C3}', '\u{00D5}', '\u{0152}', '\u{0153}',
    '\u{2013}', '\u{2014}', '\u{201C}', '\u{201D}', '\u{2018}', '\u{2019}', '\u{00F7}', '\u{25CA}',
    '\u{00FF}', '\u{0178}', '\u{2044}', '\u{20AC}', '\u{2039}', '\u{203A}', '\u{FB01}', '\u{FB02}',
    '\u{2021}', '\u{00B7}', '\u{201A}', '\u{201E}', '\u{2030}', '\u{00C2}', '\u{00CA}', '\u{00C1}',
    '\u{00CB}', '\u{00C8}', '\u{00CD}', '\u{00CE}', '\u{00CF}', '\u{00CC}', '\u{00D3}', '\u{00D4}',
    '\u{F8FF}', '\u{00D2}', '\u{00DA}', '\u{00DB}', '\u{00D9}', '\u{0131}', '\u{02C6}', '\u{02DC}',
    '\u{00AF}', '\u{02D8}', '\u{02D9}', '\u{02DA}', '\u{00B8}', '\u{02DD}', '\u{02DB}', '\u{02C7}',
];

pub(crate) fn decode_mac_roman(bytes: &[u8]) -> String {
    bytes
        .iter()
        .map(|&byte| {
            if byte < 0x80 {
                byte as char
            } else {
                MAC_ROMAN_HIGH[(byte - 0x80) as usize]
            }
        })
        .collect()
}

pub(crate) fn decode_mac_roman_for_render(bytes: &[u8]) -> String {
    let mut out = String::with_capacity(bytes.len());
    for &byte in bytes {
        match byte {
            0x00..=0x7F => out.push(byte as char),
            // The HLE chrome renderer only has ASCII glyphs plus a few symbol
            // slots, so expand common punctuation into renderable forms.
            0xA5 => out.push('*'),
            0xC9 => out.push_str("..."),
            0xCA => out.push(' '),
            0xD0 | 0xD1 => out.push('-'),
            0xD2 | 0xD3 => out.push('"'),
            0xD4 | 0xD5 => out.push('\''),
            _ => out.push(MAC_ROMAN_HIGH[(byte - 0x80) as usize]),
        }
    }
    out
}

pub(crate) fn encode_mac_roman_lossy(value: &str) -> Vec<u8> {
    value
        .chars()
        .map(|ch| {
            if ch.is_ascii() {
                ch as u8
            } else {
                MAC_ROMAN_HIGH
                    .iter()
                    .position(|&candidate| candidate == ch)
                    .map(|idx| idx as u8 + 0x80)
                    .unwrap_or(b'?')
            }
        })
        .collect()
}